JPH01230105A - Tool posture control method for robot - Google Patents

Abstract

PURPOSE:To control the direction of a tool in an intentional direction by interpolating the inclination angle of a tool from the starting point and the termination of the work point of a robot and the reference plane of respective points, the direction angle of the tool and the rotation angle around the tool between the starting point and the termination respectively and driving the robot. CONSTITUTION:Interpolation for a variation (theta1'-theta1) of a tool inclination for a reference plane 1 with a starting point P1 and a termination P2, the interpolation for a variation (theta2'-theta2) of the direction (rotation angle from reference line 3) of the tool projected on the reference plane 1 and the interpolation for a rotation quantity (theta3'-theta3) around the tool are executed, and while the tool passes through a circular arc channel 2 from the starting point P1, three angles to show the posture of the tool are linearly changed from theta1 to theta1', from theta2' to theta2 and from theta3' to theta3. Thus, by designating the direction of the tool of the starting point P1 and the termination P2 so that the tool can be directed to the inside of the circular arc, the tool is always directed to the inside of a circular arc during the movement.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tool attitude control method in an industrial robot.

Conventional technology Conventionally, tool posture control in industrial robots involves linearly interpolating two angles: the rotation angle of the tool direction and the rotation angle around the tool between the start point and the end point. The posture of the tool is controlled by

FIG. 5 is an explanatory diagram of this conventional tool posture control, in which it is assumed that the direction of the tool at the starting point P1 is indicated by the approach vector ■1. Then, at the end point P2, the direction of the tool is indicated by the vector v2, and the rotation angle θ1 of the tool direction, that is, the vector V1' when the vector ■1 is translated in parallel from the start point P1 to the end point P2, is the vector V1'. The rotation angle θ1 obtained by rotating the vector V1' to the vector ■2 around the axis passing through the end point P2 perpendicular to the plane through which V1' and the vector ■2 pass, and the rotation angle around the tool axis (rotation around the approach axis) Angle) θ2 is linearly interpolated between the starting point and the ending point to control the tool posture.

Problems to be Solved by the Invention In the conventional method of controlling the attitude of the tool using the rotation angle θ1 of the tool orientation and the rotation angle θ2 around the axis of the tool, the tool does not move in the intended direction while moving from the starting point to the ending point. It may not be suitable for This problem particularly occurs when circular interpolation is performed and the tool passes along a circular path locus. Usually, for a circular arc path, the starting point, end point, and intermediate point thereof are taught to draw the circular arc path. For example, as shown in FIG. 6, starting point P1 of a certain plane 1. When the end point P2 and the intermediate point P3 are taught, and the path of the arc 2 is taught, the direction of the tool, that is, the direction of the approach vector, is the vector V1' obtained by translating the approach vector v1 at the start point from the start point P1 to the end point P2, and the vector V1' Vector V1 on the plane passing through 2
' Since the rotation angle (rotation angle of the tool direction) θ1 from the vector V2 to the vector V2 is linearly interpolated and moved from the starting point to the ending point, it is determined in a rigid manner. That is, the orientation of the tool between the start point and the end point (approach vector V3) is determined strictly by the orientation of the tool at the start point and the end point, and the orientation of the tool at the intermediate point cannot be controlled. For example, even if you intend to move the tool so that it faces inside an arc, this will not work as intended. This is especially bad when the path exceeds half a circle, even if the tool points inside the arc at the start and end points.
In the middle, the tool will be oriented toward the outside of the arc.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a tool posture control method that can control the orientation of a tool even during movement from a starting point to an ending point.

Means for Solving the Problems The present invention solves the problems by determining the positions of the starting and ending points of the robot's work points, the inclination angle of the tool from the reference plane at the starting and ending points, the orientation angle of the tool projected onto the reference plane, and the rotation angle around the tool. The above problem was solved by driving the robot by interpolating between the starting point and the ending point, respectively.

Operation FIG. 1 is an explanatory diagram of the operation principle of the present invention, and a straight line or circular arc from a starting point P1 to an end point P2 is taught, and from the starting point P1. The direction of the tool at the end point P2, that is, the approach vector V1.
The inclination angles of V2 from the reference V plane (plane passing the starting point P1° and ending point P2) 1 are respectively θ1 and θ1', and the reference line on the reference plane (for example, the X-axis or in the case of an arc trajectory, the arc center and the starting point are The rotation angle of the tool projected onto the reference plane 1 from the reference line) 3, which measures the amount of rotation of the tool projected onto the reference plane 1, such as a connecting line, is determined by θ2. θ2', and the rotation angles around the tool axis are respectively θ3. Assuming θ3', the present invention is based on the starting point P
The position is interpolated from 1 to the end point P2, and the above 3
An interpolation of two angles is performed. Therefore, the rotation amount of the tool inclination (θ1'-θ1) and the rotation amount of the tool orientation projected on the reference plane (θ2', -θ2) are also interpolated, so the tool inclination is linear from θ1 to θ1'. The orientation of the tool changed and projected onto the reference plane also changes linearly from 02 to 62'. In this way, the orientation of the tool is controlled by the inclination of the tool with respect to the reference plane (θ1, θ1') and the orientation of the tool projected onto the reference plane (θ2, θ2'), so even during the path from the start point to the end point, It is possible to obtain the intended orientation of the tool.

Embodiment FIG. 2 is a block diagram of an industrial robot implementing the method of the present invention. Reference numeral 20 denotes a control device of the robot, 30 a mechanism section of the robot, and 40 a work object to be worked by the robot. The control device 20 has a central processing unit (hereinafter referred to as CPU) 21, and the CPU 21 includes a memory 22. Memory 23 consisting of RAM for storing teaching data, etc. Teaching operation panel 24 for teaching movements to the robot. Operation panel 25 for inputting various commands, etc. An axis controller 26 for driving a servo motor for each axis of the robot mechanism section 30 via a servo circuit 27 and an interface 28 for transmitting and receiving signals with a work object 40 are connected by a bus 29 .

The configuration of the above-mentioned industrial robot is the same as the conventional one, and the details will be omitted.

Therefore, the operation processing when performing tool posture control will be explained together with operation 70--Diaert in FIG.

First, the CPU 1 reads one block of the teaching program from the memory 23 (step S1), and then reads the coordinate position (X) of the current working point (starting point) of the robot.

Y, Z) and three angles θ1 (inclination of the tool from the reference plane), θ2 (orientation of the tool projected onto the reference plane), and θ3 (rotation around the tool) that indicate the attitude of the tool are determined (Step S2). , the coordinate position of the target point read in step S1, that is, the end point @(X.

Y, Z) and tool posture θ1. θ2. θ3 is determined (step 83). The starting point found in steps 82.83,
From the coordinate position (X, Y, Z) of the end point, three angles θ1°θ2. Complementary interpolation processing is performed to interpolate the movement angle of θ3 (step 84).
. Next, the interpolation points obtained by complementary interpolation are converted into joint angles of each joint of the robot (step S5), and this 1!1
Interpolation is performed for the rotational error of the nodal angle, pulses are distributed, and the servo motors of each axis of the robot are driven (step 86).

Then, it is determined whether the processing of one block has been completed or whether the target point has been reached (step 87), and if it has not been completed, the processing from steps 84 to S7 is repeated again. When the processing of one block is completed, the next block is read (step S8), and if the program is not completed (step S9), the processing from step 82 onwards is repeated again until the program is completed.

The above is the operation processing of the present invention, and FIG. 4 shows the operation when the robot is taught an arcuate route according to the present invention.

Starting point P1. The positions of the end point P2 and its intermediate point P3 are taught, and three angles 01 indicating the tool posture at the end point P2 are taught.
', θ2', 03' are taught and an arc command is issued, the position is interpolated from the starting point P1 to the ending point P2, and the amount of change in tool inclination (θ1' -61), reference plane 1
Interpolation is performed between changes (62'-θ2) in the direction of the tool (rotation angle from reference line 3) projected on the image plane, and interpolation is performed for rotations around the tool (03'-03), and the tool moves along an arcuate path from the starting point P1. The three angles that indicate the attitude of the tool while passing through 2 are 01' from θ1, 62 from θ2',
It changes linearly from θ3' to 03. Therefore, set the starting point P1 so that the tool faces inside the arc. If the direction of the tool at the end point P2 is specified, the tool faces inside the arc as it moves from the start point P1 to the end point P2. In particular, in the case of an arc path that goes around a circle, the amount of change in the orientation of the tool projected onto the M quasi-plane 1 is approximately 360 degrees, and this 360 degree is interpolated while the tool goes around the circle. , you can see that the tool always faces inside the arc. In this respect, the conventional method differs greatly in that the tool faces outward in the middle of the arcuate path.

Effects of the Invention The present invention allows the tool to maintain its orientation as intended at the time of teaching.
Particularly in the case of circular interpolation, the orientation of the tool, which could not be controlled in the past, can be controlled to the intended orientation.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the working principle of the present invention, Fig. 2 is a block diagram of an industrial robot implementing the present invention, Fig. 3 is a flow chart of the operation processing of the same embodiment, and Fig. 4 is a diagram according to the present invention. FIG. 5 is an explanatory diagram of conventional tool attitude control; FIG. 6 is an explanatory diagram of circular arc route operation in conventional tool attitude control. 1...Reference plane, 2...Route, 3...Reference line, V
l, V2. V3... Approach vector, θ1,01
'...Inclination angle of the tool from the reference plane, θ2. θ2
'... Orientation angle of the tool projected onto the reference plane, θ3.
03'...Rotation angle around the tool. Figure 1 Figure 3 Figure 5

Claims (1)

[Claims] The positions of the robot's starting and ending points, the inclination angle of the tool from the reference plane at the starting and ending points, the orientation angle of the tool projected onto the reference plane, and the rotation angle around the tool are interpolated between the starting and ending points, respectively. A robot tool posture control method characterized by driving the robot.